October 29, 2015 Princeton, New Jersey - Back on December 14, 2002, I did my first Earthfiles report about the North Atlantic Oscillation that combines with the North Atlantic Drift like a big conveyor belt that brings warm Gulf of Mexico waters northward, warming temperatures along eastern North America and western Europe. Back then the journal Science had published findings that six of the world's biggest fresh water rivers in Eurasia were dumping a lot more water into the Arctic Ocean due to melting perma frost and glaciers as the Earth is warming up. The concern was whether all that fresh water would dilute the salty North Atlantic enough to slow down, even stop, the big conveyor belt that is also called the Atlantic Ocean's "Meridional overturning circulation," or AMOC. AMOC is driven by differences in ocean temperature and the salt content in the North Atlantic.

Today in October 2015, even more fresh water is melting off of Greenland into the North Atlantic adding fuel to the scientific controversy about whether the big warming conveyor belt will be so diluted that there won't be enough salt necessary to sink cold water that drives the circulation.

Adding to the confusion now is that in spite of great heat in both the air and water of the Gulf and 2014 going down in the record books as the hottest worldwide year yet, a huge "blob" of abnormally cold water has been observed in the north Atlantic Ocean beginning two years ago. The giant mass of record-breaking cold water is between southern Greenland and Europe. It is assumed to be Greenland ice melt runoff, but no one knows why the massive cold blob keeps growing unaffected by the Gulf waters moving north.

Earlier in 2015, climate scientist Michael Mann of Penn State and Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research published a paper in the March 2015 issue of Nature Climate Change reporting data that the Atlantic Meridional Overturning Circulation is growing weaker.

Mann's and Rahmstorf's concerns are if the data persists and the conveyor belt grows weaker, one of many consequences will be rising sea levels for the U. S. East Coast and possibly cooler temperatures overall in the North Atlantic and Europe.

Reinforcing this concern has been James Hansen, who was head of NASA Goddard Institute for Space Studies from 1981 to 2013. He now directs the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute. He and 16 other prominent climate researchers collaborated on a July 2015 paper in which they said: “If the ocean continues to accumulate heat and increase melting of marine-terminating ice shelves of Antarctica and Greenland, a point will be reached at which it is impossible to avoid large scale ice sheet disintegration with sea level rise of at least several meters.”

I took all of this to Thomas L. Delworth, Ph.D., Research Scientist, NOAA's Geophysical Fluid Dynamics Laboratory and Professor of Atmospheric and Oceanic Sciences Program at Princeton University in New Jersey. He confirmed the huge cold blob in the Northern Atlantic is puzzling and not understood.